Meeting Abstract
Intraspecific studies of morphology and performance are essential for understanding the factors that enable resource partitioning within ecological communities, yet these have received little attention in mammal ecomorphology. Sea otters (Enhydra lutris) is one of the few marine mammal species in which individual-level dietary specialization has been quantified and linked to competition and prey abundance, making them an ideal system to investigate the morphological basis of food resource partitioning. Here, we assess whether differences in cranial morphology and bite force predict dietary variation among sea otter populations. We use geometric morphometric analyses and two-dimensional bite force models to (1) estimate differences in cranial shape and bite force among the three sea otter subspecies groups, E. l. kenyoni, E. l. lutris and E. l. nereis, (2) evaluate the extent of sexual dimorphism in cranial morphology and bite force within subspecies, and (3) relate the variation in cranial morphology and bite force to available dietary information. Although some sexual dimorphism in cranial features exists, preliminary results do not show significant differences in bite force between subspecies or between male and female sea otters. These results suggest that resource-use variation may be linked to individual foraging behavior and not to differences in morphology in sea otters. However, unique cranial features leading to high bite forces may enable this species to have higher diet plasticity; higher bite force in sea otters allows for the consumption of a variety of hard-bodied prey items and allows for either generalized or specialized diets, depending on prey availability and competition.
